Converting an ole motor boat to a trimaran, AND sailboat

[Lonejack]

Hi new friends,
Just joined, love reading the various posts.
Please don't kick me out of the forum for daring to broach this subject.
I live close to a major river in the Western U.S. As my Bride and I drive around sightseeing,
I see hundreds of motor boats sitting with weeds growing over them.
I have seen where some here have converted a monohull to a trimaran. Has anyone attempted to
convert a motor boat to a sailboat or a trimaran?
I know it could be a slug, but one could sure have a lot of fun trying.
My thought would be to find a free Hobby cat and use the amas for stability, mount a mast-aft and
use furling jib and genoa. Lots of deck room and with tramps, would allow for a great swimming platform. River and small water only.
Max outlay, $500.

 

[Mr Efficiency]

What motor boats do you have in mind ? Planing hulls ?

 

[JamesG123]

Those boats are usually laying derelict for a reason, bad motor or bad rotten hull. Either that is what got them there or that is where they are now after years (decades?) of being left improperly to the elements.

If you have more time than money (or sense), then yeah, anything is possible. But it will hardly be easy. It takes a ton of not fun work to get those old hulks cleaned up and functional enough to put back into the water. And that is without trying to convert one to a motor sailer.

 

[Lonejack]

These boats are mostly fiberglass. Wouldn't touch a wood hull.
Almost 100% of these are planing hulls. I was just looking on Craigslist, there are many free boats offered, with trailers.
I'm not planning on building an America's Cup yacht, just going to go through the process and have the fun of designing the craft.
Probably will use unusual materials for the mast, rigging and sails. Yep, it will probably be a crude failure that ends up in the land fill.
I'm looking for a weekend river cruiser. May race another Who knows... The challenge is intoxicating.
I am a retired designer who was born and raised on a post depression wheat ranch, located 6 miles from the nearest town.
We had to design. build and maintain most of our own farming equipment. My father patented a farm machine and invented
a rotary steam engine among other things. I inherited his design bug.
Love to design and build something from repurposed material.
Hey, I'm retired, every day is Saturday, except Sunday. I have a full shop, Gotta do somthin.

 

[Mr Efficiency]

Get two planing hulls that are the same boat, and join them end-to-end (stern to stern), that way at least the thing will move through the water relatively easily, a planing hull has too much resistance.

 

[JamesG123]

These boats are mostly fiberglass. Wouldn't touch a wood hull.

Most fiberglass boats, esp. older ones, have a lot of wood in them. In the flooring and between the glass. Fiberglass itself can also go bad if neglected long enough. A "free boat" is just one where your first payment has been deferred.

But if you think you know what you are getting into...

 

[ondarvr]

$500.00 won’t get a “free” boat back to your house.

 

[kapnD]

As Mr Efficiency has noted, planing hulls make lousy sailboats, you need to do some research on efficient sail driven hulls before you move on the idea.
I’ve seen powerboat hulls split in half to make catamarans, but that doesn’t really do anything besides making them heavier and more stable, and it’ll still be a powerboat hull, and a poor sailer.

 

[trip the light fandango]

Get two planing hulls that are the same boat, and join them end-to-end (stern to stern), that way at least the thing will move through the water relatively easily, a planing hull has too much resistance.

A 30ft long boat about 2metres.6;6 wide would make a good river/lake craft, if you kept the weight around waterline or below this could be a remarkable for good reasons craft. 2 boats the same with a well thought out join, with inflatable tubes in or roped onto the gunnels, long and skinny it would move through the water well. That could be worth the risk of failure.

 

[kapnD]

A 30ft long boat about 2metres.6;6 wide would make a good river/lake craft

I haven’t seen any fiberglass powerboat hulls with dimensions anywhere near 30’ x 6’6”.
Two hulls joined together just doubles the drag, not going to sail well, especially with low tech sails.
My kids have been having tons of fun with an old truck inner tube and a salvaged windsurfer kite, so there are alternatives to cheap fun without the complexities of a full-on boat, try looking outside the box!

 

[upchurchmr]

There are lots of derelict fiberglass sailboats which would make a better main hull for a trimaran.
Get the narrowest one you can find.
Hobbie cat hulls don't have much flotation.
If you can find Nacra or Tornado hulls they will work much better.

All that weight will need more sail, not less.
Perhaps an old Tornado mast/ sails would work.
16' Hobbie cat rigs are more plentiful and almost the same size. The mast is also shorter (5' less) and lighter. I got a whole boat for $100 a year ago. The hulls were complete trash, which is typical.

There are articles about a Soling that was converted to a Tri on line, Google.
Also a Chrysler 22 which seemed to work good.

Good luck. $500 is probably a little low, but good for daydreaming!
Keep updating this thread please - I want to see it.

Marc

 

[trip the light fandango]

I haven’t seen any fiberglass powerboat hulls with dimensions anywhere near 30’ x 6’6”.

No,
but lots of 15 ft x 6;6 I should have made that clearer. I prefer tri's and they generally need to be light or the joins are either works of art or very strong and heavy or both. 2 half cabs butt joined could be a good thing, ha. or why not a proa , now that could work... maybe, cheers

 

[Mr Efficiency]

No,
but lots of 15 ft x 6;6 I should have made that clearer. I prefer tri's and they generally need to be light or the joins are either works of art or very strong and heavy or both. 2 half cabs butt joined could be a good thing, ha. or why not a proa , now that could work... maybe, cheers

Pick them up for peanuts, the transoms are stuffed, who cares, we just have to do a good "graft" of the two sterns, with some through stringers, and have a nice double ender !